ad5323 using as programmable attenuator

1. I supposed to use 'REF' as input pin. Also, the noise of this input signal is already known. However, I don't see any information about how much noise this DAC may contribute. So I want to know does this mean DAC won't contribute any noise or how can I calculate this noise.

2. I have noticed that most of your DAC chips are based on the principle of resistance net according to datasheet. Do you have any charge redistribution DAC? Cause I think capacitor would have better noise performance than resistance.

1) As AD5323 does not have any information on noise performance/spec, would you consider using AD5687? You can find the noise specs under AC characteristics of the datasheet. More info on NSD can be found on this tutorial and this video.

2) I'm pretty sure capacitance based DACs have its advantages (and disadvantages too) on some applications, however in the precision space we currently offer resistor based architectures.